1. Field of the Invention
The invention relates to the preparation of pellicles of para-xylylene polymers.
2. Description of the Prior Art
Pellicles are relatively thin free-films of limited surface area. Pellicles made of para-xylylene polymers have been used in optical devices as beam splitters and for other purposes such as radiation windows; low mass supports for various types of devices such as hypervelocity particle detectors; and diffraction grating replicas.
The films may also be retained on a substrate as a coating therefor.
For many of such applications it is sometimes desirable to employ a pellicle of para-xylylene polymer which has a non-uniform cross section. Because of the nature of the process in which such polymers are usually prepared on a commercial scale, i.e., from a vaporous precursor and under vacuum conditions, and because of the delicate nature and relatively small size of the pellicles, it has not been possible to date to readily prepare a variety of pellicles having a non-uniform cross section.